The cloud servers have routinely adopted machine virtualization for high energy efficiency. Such virtualization notably improves energy efficiency not only through consolidation, but also through Dynamic Voltage/Frequency Scaling (DVFS). Thus, current hypervisors such as Xen and KVM support power management (PM) policies statically or dynamically setting a Voltage/Frequency (V/F) level, similar to ones deployed by the Linux. However, the current hypervisors can promote only a single PM policy (i.e., host governor) per physical core. This poses a unique challenge for VMs sharing a physical core and running applications with opposite runtime characteristics in a time-shared manner (i.e., heterogeneous VMs); note that the consolidation policy often encourages heterogeneous VMs to share a physical core, since such VMs use different resources in the system .